I'm not trans. I couldn't even be considered a tomboy. Why would my dad joke about me being trans? Do you think it's related to me sexuality?
Is he just the kinda guy known for 'off-color' jokes? And are you out to him as a lesbian? Because maybe he's just playing off that stereotype that lesbians feel like men. I mean, I don't know what to tell you unless you elaborate.
Some people honestly don't differentiate between sexuality and gender identity just because they don't think about it. "If you like girls, you must be mentally a dude!" A lesson I tell myself almost daily is that *everything* in life is more complex than what people see on the surface. But some people don't realize that and make gross generalizations without even knowing it.
My mother told everyone she knew I was trans "like Chaz Bono", plunging me into a manufactured gender identity crisis, and forcing awkward conversations with relatives to clarify that no I am not nor do I intend to ever become a woman, I am a gay male (she had also outed me as gay to everyone she knew without asking me, but at that point I wasn't going to deny it) ...all because she found out I was wearing girls' leggings. So of course I had to defend my clothing choices to people like my aunt as well as my mother. I told my my mother I think it looks good on me, it's a piece of fabric, it doesn't have a penis or a vagina- I think that's the first time in my life I've ever used the words "penis" or "vagina" with my mother. Maybe it's technically cross-dressing and falls under the transgender "umbrella", but I am not transsexual "like Chaz Bono" and in any event it's up to me how I identify myself and I identify as a gay male, even if femme. Unless I had identified myself to her as trans, she had no right to 'out' me as trans. (Actually she didn't really have the right to 'out' me as gay either, even though I had identified myself to her, privately, as gay.) Sometimes it seems that people can't tell the difference gay/lesbian and trans. If you're a femme gay guy or a butch lesbian, people who aren't so bright assume you must want to actually be the other sex. I mean, there are still some homophobic idiots out there who believe homosexuality means you want to be the other sex, even if you're a manly gay man or a girly lesbian girl. A father will say having a gay son is like having a daughter, while a mother will say having a lesbian daughter is like having a son. How serious is the tone of his voice when he 'jokes' about you being trans? Is it just a pure joke or does it sound like he actually believes it and thinks there is a kernel of truth within it? Sometimes jokes are purely absurd and not to be taken seriously, other times jokes are considered funny because they hit on some underlying truth.
I think he was joking. I'm not butch, but I'm not overly girly. I'm just as feminine as the average girl. I'm actually a bit more femme than my straight sister.
Maybe his way of dealing with your sexuality is to make a joke of it. Im not saying its a good way of dealing with it but maybe that is how he copes with things that he finds difficult.
People joke about things to try and make them more comfortable, maybe he's just trying to lighten the mood but didn't realise you'd not like it..? If you're out to him it could be him trying to 'break the ice' with you and make everyone more at ease? How does he say it and what was the situation he said it in?