PORTLAND, Ore. (Reuters) - "I love my lesbian moms," read a hand-lettered sign a teen-ager held up recently to motorists passing a county building in Portland, Oregon, where gay couples lined up to get marriage licenses. The message, prompted by the heated national debate over gay marriage, underscored a growing phenomenon -- lesbian couples having babies and raising families. According to the Family Pride Coalition, a national advocacy group for gay and lesbian families, some 9 million children in America have at least one gay parent and one in five lesbian coupled households include a child under 18. "I wouldn't...