More than half of women are attracted to other women - and it gets more pronounced as they get older Most women are naturally bi-curious when it comes to sex, a new report has discovered. And what's more, it becomes more pronounced the older they get. The latest research simply claims it perfectly normal. Boise State University found in a group of 484 heterosexual women, 60 percent were sexually attracted to other women; 45 percent had kissed a woman, and 50 percent had fantasies about the same sex. Elizabeth Morgan, a professor of psychology at Boise State University, studies same-sex attractions among heterosexuals and finds that straight women often feel more than a friendly affection for other women. Mary Portas was 49 when she entered into a civil partnership with 37-year-old Grazia journalist Melanie Rickey last year after calling time on her 13 year marriage with husband Graham Other data suggests upwards of 20 percent of women are attracted to other women. It's claimed this could be linked to the way women socialise from chatting on the phone for hours to snuggling during chick flicks. It's said often women's friendships are barely distinguishable from romantic relationships. Prof Morgan said: 'Women are encouraged to be emotionally close to each other. 'That provides an opportunity for intimacy and romantic feelings to develop.' And over 15 years, Lisa Diamond, Ph.D. a psychologist at the University of Utah, followed a group of women attracted to other women. Her data shows, for the first time, how sexuality develops over a lifetime. At each of the half dozen follow-ups interviews, she asked each woman to label herself as lesbian, bisexual, heterosexual or unlabeled and share details about her love life. The findings startled even her. Over time, each woman's chosen labels changed repeatedly, with one noteworthy trend. Ms Diamond said the older they got, the more likely they were to choose 'unlabeled' which mean the older they got, the more they felt their sexuality didn't fit into tidy boxes. She said: 'We have this idea that sexuality gets clearer and more defined as time goes on. 'We consider that a sign of maturity to figure out who you are. I've seen it's really the opposite.' The survey results will certainly ring true with retail guru Mary Portas. The presenter of the BBCs Mary, Queen of Shops recently entered a civil partnership with Grazia magazine fashion editor Melanie Rickey, having ended her 13-year marriage. At the time, Portas told the Guardian she could not define whether she felt like a lesbian or a straight woman who had fallen in love with another woman.MARY PORTAS' STORY 'When you look at female sexuality its very different. Lots of women have been in love with men and then women and vice versa, its just not so defined and I couldnt explain it in black and white. 'Have I loved men? Yes. Have I loved more than one woman? No. But did I know that Id had crushes on men and women in the past? Yes. So it was never like, oooh! But was I happy in my heterosexual relationships? Yes. Thats the way it just happened.' Portas had an amicable divorce from her husband, with whom she has two teenage children - in fact, her husband was the first person she told about Melanie. She added: 'I certainly wasnt a suppressed lesbian thinking, God, I cant wait to get out of this marriage, cos that would be just awful, awful, awful. 'I just happened to fall in love with a woman.'