So I was thinking about writing an essay about my parents not accepting gay people, which is ironic because I am gay myself (although they don’t know). I don’t want to seem like someone who fights with their parents on this issue and disrespects them, but I also want to show admission officers I do fight to get what I want (although, again, I am not out to my parents) Is this a bad essay topic? Honesty is appreciated 
There are very few bad topics, only bad essays. Write it and then see how you feel about it.
BUT (and you knew that was coming, right?) Make sure it passes the college essay litmus test: Does it give them a reason to say yes to your application? Is it about YOU (and not your parents, not about being gay, not about tolerance)? Does it show you to be the kind of person they want on their campus-- not as gay or straight, but because of the things you do and who you are?
If so, then it’s a good topic. If not, then you need another.
Totally agree with @bjkmom . The topic is fine if you write about who you are. If this influences who you are or is the backdrop for a scene depicting that, no problem. Just take care to keep the focus there, not on your parents. When the AO is done reading, you want him to have an insight into who you are.