When she was a teenager, her parents moved from the stricter Presbyterian denomination of her mother to the more free-thinking Unitarianism preferred by her father.

But many years after she had converted to Orthodox Judaism, Malka discovered that her father's Kramer ancestors were 19th century German Jews.

Malka, who recently stepped down as Bar Ilan University dean of exact sciences, told me: "Maybe that was why my father's family preferred Unitarianism because it was closer to Judaism.

"Maybe there was a grandmother back there in Europe davening for me."

But back then as a teenager Mary was gradually losing her faith in God. But, a seriously academic student, she held onto her belief in morality and delved into philosophy to try to discover it there.

"I was looking for a basis for morality," she said. "I first looked for it in philosophy. I started with Socrates and worked my way forward through Kant, Hume and Locke and Leibniz. They really believed that you should be able to get there with philosophy, but they didn't convince me."

At college, Mary began to make Jewish friends. Even though they were assimilated Jews, she was impressed by the "staying power and discipline even in people two or three generations on".

One example was when she was making a bacon and eggs breakfast for two Jewish friends who, she said "really didn't seem any different from anybody else".

Malka recalled: "One of them said, leave out the bacon for me. The other said, if you leave out the bacon for her, leave it out for me."

Later when spending a term on mathematical research in Germany, "under the shadow of the Holocaust", Mary ran out of matches when cooking in the university dorm.

By this time, bacon and all meat had become removed from her diet as she tried to adopt a more Jewish way of life. Wanting to cook just eggs, Mary came up against a moral dilemma. She had run out of matches. Should she 'steal' one from the drawer of one of her fellow students?

She seriously decided: "Even if it's a very small and cheap thing, it's still stealing. I felt that the decisions you are constantly making to keep kosher and Shabbat make you aware of other moral issues."

She first converted to Conservative Judaism, but finding it not strict enough for her liking, re-converted Orthodox, by which time she had met her future husband, Professor David Schaps, when they were both studying for their doctorates at Harvard University and were the only two people on campus who kept kosher.

On gaining their doctorates, the couple decided to pursue academic careers in Israel; he in classics and Mary in mathematics.

Beginning by working at Tel Aviv University and then moving onto Bar Ilan, they opted to live in the ultra-Orthodox enclave of Bnei Brak, with Mary becoming Malka, behaving and dressing as a charedi woman, despite the fact that she was a leading academic in her field and active in fighting for greater equality for women in academia.

With charedim normally shunning the academia, it wasn't easy for Malka to reconcile the two worlds, but she has succeeded to the extent that she is now highly regarded, not only by her academic colleagues, but also by charedim all over the world.

Malka and David were only able to have two children. But two is an extremely small family by Bnei Brak standards, so they made up the numbers by fostering, which wasn't easy.

She told me: "There is a lot of heartbreak in being foster parents. We raised two foster children till they got married."

The issues still continue. At the recent barmitzvah of a foster son's son there was a separate table for the foster child's family.

So how did Malka manage all the disparate elements in her life, as she juggled to be the perfect Bnei Brak woman and Bar Ilan professor and dean?

An answer came by adopting her third persona, that of author Rachel Pomerantz.

Once Malka had got tenure and felt secure in her university post and had some time to fill she decided to write, something she had always enjoyed.

Her novels, mainly geared for the charedi market, are largely biographical, exploring her own issues of juggling her different worlds.

One of her reasons for writing was to try to explain to her mother, who died last year, aged 100, why she had decided to convert to Judaism.

Her mother proudly displayed Rachel Pomerantz's books on her bookshelves, but never quite understood why her daughter did not remain a Unitarian.

Malka decided to adopt a pen name for two reasons. Firstly, because academics were not always taken seriously professionally if they wrote fiction.

And secondly, because when Malka started writing in the 1980s, there was no adult fiction being written for the charedi market.

Malka did not want the fact that she was a pioneering adult fiction writer to spoil her children's chances of good charedi shidduchim (matrimonial matches).

The first book she wrote, but not the first to be published, A Time to Rend, A Time to Sew, told the story of two Jewish American sisters who became more religious and had to decide between their careers and their families. One manages to juggle the two while the other abandons her career.

The analogies to Malka are obvious. But in the early 1980s, the charedi publishers were afraid that Malka's subject matter was too open for their market, which only read Jewish books and knew nothing of the outside world.

So she went for the safer option of telling the true stories of Holocaust survivors in Wings Above the Flames. This was followed by World in Flames, a history of the Holocaust.

She then wrote Wildflower, which told the story of a childless couple who foster a child, only to have it reclaimed by its natural parents.

Malka said: "The editors of publishers took what they felt to be a risk in publishing Wildflower, which contained such sensitive topics as fertility treatments and a married couple who separate. CIS did not, in fact, use their own label for this label.

"When the book was successful, the field was open for more of the same."

Having made it into the charedi world as Rachel Pomerantz, Malka was able to disclose her identity.

She said: "I didn't tell anyone at work when I was writing. But it's not much fun writing a book if you don't tell anyone about it. Most of the people who knew me, knew anyway. All my books were on my shelf at work and people realised they had to read them."

Today her nine books are popular in the charedi world, although, she says: "Seminaries are more careful and probably won't put my books in their libraries."

Then three years ago Malka took the Israeli academic world by storm by becoming the first woman to be appointed a university dean of exact sciences.

During her term as dean, Malka had no time for writing, but she is now embarking on a novel about women and academic politics and is looking to venture outside the charedi and even Jewish market into the wider world of publishing.

She said: "The novel is about the only woman in her maths department in Chicago, who is elected chair. It is about my experiences as chair and as dean. I am trying for trade publishing.

"Although there is a Jewish sub-plot, the main plot is mainstream American and deals with other cultures."

So what is the position of women in Israeli academia and what does the charedi world think of her prominent position in it?

One of the difficulties for university women, she said, was that Israeli academics were now expected to spend time on post-docs in universities abroad, which was very difficult for those with young families.

This meant that there were far fewer women professors than men. But some Israeli universities were offering post-doc supplements to ease the process.

About the charedi reaction to her success, she said: "They were very pleased when I got to be dean. It was one of ours made good."

Despite her high academic position, or maybe because of it, her Bnei Brak neighbours are happy to send their children to her for maths tuition.

But they are suspicious that the modern-Orthodox Bar Ilan University will try to encourage charedi students to become less rigorous in their observance.

But Bar Ilan has pioneered separate courses for charedi men and women.

Although she is technically retiring at the end of the year, Malka is to continue teaching and research.

She said: "The social worker for the faculty recommends people to continue teaching. She thinks it is mentally healthier."

And just in case Malka fears she has not enough mental stimulation, she has started learning her husband's speciality, classical Greek.