�Dirty Minds,� by Kayt Sukel; �Straight,� by Hanne Blank; and �How We Love Now,� by Suzanne Braun Levine

Will the 21st century change the ways we think about sexual orientation, romantic attraction, love and fidelity? Our sources of information and solace have certainly changed, as science writer Kayt Sukel points out: �Instead of Mom�s shoulder, Freud�s couch, or the pastor�s office, we now look for answers in genetic profiles and brain scanners.�

But science has yet to come up with matchmaking formulas that would make online dating, or The Washington Post�s Date Lab, a reliable predictor of compatability. Science hasn�t been able to identify a gay gene or, for that matter, a straight gene; it can�t outdo Mom, Freud or the pastor in explaining transgender people. After Chaz Bono became a celebrity on �Dancing with the Stars,� he dumped the girlfriend who had stuck by him through years of his surgical and hormonal change from female to male � strong evidence to me that the operations were successful, but nothing that would show up in a brain scan. We know that technology has changed the way young people find partners, but is it also changing the rules for older men and women? These three books offer both scientific and anecdotal takes on the way we love now.