Very early writers thought sexual orientation connects to the gender expression of the person. Karl Heinrich Ulrichs, Richard von Krafft-Ebing, Magnus Hirschfeld, Havelock Ellis, Carl Jung, and Sigmund Freud are some of the more famous writers. It was thought that a female person with attraction to female people is always masculine. Just the same, it was thought that a male person with attraction to male people is always feminine. This understanding of homosexuality as sexual inversion was a discussion at the time. By the second half of the 1900s, gender identity was seen as different from sexual orientation. Transgender and cisgender people may be attracted to men, women, or both. A homosexual, heterosexual, or bisexual person may be masculine, feminine, or androgynous. Still, studies by J. Michael Bailey and Kenneth Zucker say most of the gay men and lesbians describe different degrees of not matching gender roles as a child.