I stay in a different city away from my parents. So I had a conversation over the phone with my mom that went like this...
Me: Hi ma. How are you .. How was your day.
Mom: my day was good... (And then we spoke a little about general stuff and after a minute...)
Mom: I need you to get your estrogen level checked and I need to see the report this weekend..
Me: Why ma what makes you say that
Mom: because you look like a girl honey. I know something is up with you. Are you gay?
So here was my chance and I blew it..

. I took the opportunity presented in the question to escape. This is what I said instead...
Me: Ma.. I am not going to answer the question either way. So what of I am gay. There is nothing either of us can do about it, right? I hope you still accept me, I will always remain your child you know..
Mom: so are you saying that you are gay?
Me: I am not answering that question (that part is so true, I am still exploring my sexuality.., so I couldn't answer the question even if I wanted to)
Then my mom's response was pretty encouraging...
Mom: well I know something is up with you. And I am your mother and need to know everything about you and I am there for you no matter what. Please just be honest with me...
I burst into tears right there. I plan on telling mom when I go home in December for Christmas.., keeping my fingers crossed that I will more courage than what I did on the phone..