As gay couples race to the altar in California this week, scientists may have found an answer to the so-called gay paradox. Studies suggest that homosexuality is at least partly genetic. And although homosexuals have far fewer children than heterosexuals, so-called gay genes apparently survive in the population. A new study bolsters support for an intriguing idea: These same genes may increase fertility in women. Despite some tantalizing leads over the past 2 decades, researchers have yet to isolate any genes directly linked to homosexuality. Nevertheless, a number of studies have shown that male homosexuals have more gay male relatives...