In addition to the above links, it is possible to do quite a lot of research on the subject of sexual orientation identification at various ages. A good introduction is at the National Institute of Health's Gay and Lesbian Health pages. These have links to information on coming out, social issues, etc., such as the American Psychiatric Association's page, Gay, Lesbian and Bisexual Issues. You can also get abstracts of highly technical and scholarly papers, using Pubmed. The search: "coming out" and midlife gets 70 hits. "gender identity" and midlife and women and statistics gets 243, but clicking the "limits" tab and checking "free full text" and re-entering that search gets 13 hits. In each full record (click on the full text icon to the left of the title in the list), you will need to click again on a Full Text button in the upper right. This will take quite a bit of trial and error, because full text search finds words and phrases that are used only in passing. Limiting to women, and to "title/abstract", still limiting to "free full text online", the search: "sexual orientation" and age gets 15 hits.

You can find less technical information in usa.gov, which searches not only federal but many state government web sites. It gets 98 hits for the search: "sexual orientation" "midlife". Compare Google's results for the search: "sexual orientation" "midlife" site:gov (185 hits, 67 not counting "similar" ones). Google Scholar gets only 6 hits for the search: "women's sexual orientation" "midlife" statistics, but over 900 for "sexual orientation" midlife statistics. A Google Scholar search therefore will be tricky; more so because it often links to the full text of "subscription" journal articles which will ask for username and password unless you are on campus at a suscribing institution where the publishers recognizes the IP address.

To research this thoroughly, you would certainly need to go to a large library where you could get access to commercial (subscription only) databases and journals. Possible ones to try first would be Psycinfo or Psycarticles, Socindex, Social Sciences Citation Index, and Science Citation Index. A nearby public library might even be as good as any place to start, however, because popular databases such as Masterfile or Infotrac could get full text articles that would be much less technical.