How can I explain homosexuality to my parents?

Maybe you could watch a movie with good gay representation with them. See what their reaction is like and then maybe start a conversation based on that.

my definition of homosexuality would be romantic or sexual feelings towards someone of the same gender

Show them pamphlets maybe? What i did with mine is just tell them flat out thats its okay and acceptable :)

Start the conversation like this. "Dad, why do you love Mom? How can you explain it." Wait until he finishes. Then ask Mom. Then say, this is how I feel towards, (Select Gender)

It's pretty textual to describe! A person who likes people of their same gender. Love is love, embrace yourself

Maybe tell them that it's the same kind of love that heterosexuals have for each other, just for the same gender

explain what it means first, then explain how you feel about it and how its something you cant just choose

Some people are heterosexual. Other are homosexual. It's not any more a choice than being heterosexual. It's not a disease or a perversion, it's just a bit less common than heterosexuality. And most importantly : it's not about sex, but about love. (or at least, as much as heterosexuality is :p). Attraction is like a spectrum : it can evolve in one's life, and it can stay the same all one's life.

Homosexuality is when a the same genders are attracted towards each other. They feel the physical attraction too.

Tough question. If your parents are homophobic it's gonna be hard to change their view. But it is good to teach them and remind them that homosexuality is natural and normal. You're just borned with that. Scientist are not 100% sure what causes sexuality but parents shoudn't blame themselves if their child is homosexual because as I said it's normal and natural. Around 5-10% of population is homosexual... but I'd guess it's even more like 15-20%. So it's not that small number.