I am putting up this post to provide references of relevance to the discussion.
Relevant posts in this blog:
The following are links to post that include references to the research I referred to in one of my comments.
Study on differences in mental health between homosexual and heterosexual transsexuals
Spanish brain scan study shows male to female transsexuals to be different from men
Do male to female transsexuals react differently to erotic material than cisgendered men?
The female and male copulation instincts 1
On Moser's critique of Blanchard's autogynephilia theory Part 1
On the proportion of gynephilic vs. androphilic transwomen in the population
Some scientific papers on transgender conditions include numbers on the proportion of androphilic to non-androphilic transwomen.
I have argued that in general studies indicate that a majority of transwomen are gynephilic (attracted to women). There exist, to my knowledge, no specific study that looks at this research question in isolation. I have, however, looked at a large number of studies that include data for both androphilic and gynephilic MTFs, and find that in a majority of them more than 40 percent of the MTF respondents report a gynephilic or "non-androphilic" sexual orientation, which is much higher percentages than you find in the female population at large.
Several of these studies also indicate that gynephilic transwomen are likely to transition at a later stage than androphilic ones (who most often transition in their late teens/early twenties).
The studies included below vary a lot as regards sampling, methodology and the understanding of sexual orientation. Note also that older studies may be colored by the fact that access to hormone therapy and SRS at the time required adherence to stereotypical female looks, manners, behavior and psychological traits. A sexual orientation towards men was often considered a required part of that package.
207 adult MTF transsexual:
59 (33%) classified as "homosexual" (i.e. androphilic), 116 (66%) as "non-homosexual"
Separate adolescent group: all androphilic
MtF: 73 "heterosexual" (non-androphilic) and 52 "homosexual" (androphilic) -- similar to Blanchard et al 1987
Quote: "The average heterosexual male was 8 years older at inception than the homosexual group"
Randall 1959 (according to Blanchard 1992):
25% "homosexual" (androphilic), 20% bisexual, 55% "heterosexual" (gynephilic)
Wålinder 1967 (according to Blanchard 1992):
53% predominantly or exclusively "homosexual" (i.e androphilic) experience, 20% "heterosexual", 27% denied any sexual activity. 92% were "mentally excited by males"
54 "homosexual" (androphilic) and 45 "non-homosexual"
68.5% "homosexual" (androphilic), 12.4% "heterosexual" (gynephilic), 16.8% bisexual, 2.1% asexual
234 responses from MTF transsexuals.
Scale from 1 to 4. Sexual attraction to males 3.13. Sexual attraction to females: 3.37.
Other posts of interest:
Autoandrophilia, on women who fantasise about having a man's body
What brain science says about M2F transsexuals
How many autogynephiliacs are there?
Genes, hormones, sex and gender identity