If you truly love your child comes out and tells you that they are gay you should respond with love and care for them.
Let them know that you still love them no matter what and that it's okay to be gay as everyone is different.
I know it can be hard even for parents that love their children to hear that there child is gay but it can happen and every parent should be prepared for their child to come out to them about being gay.
Although not everyone turns out gay but it's a good idea to be prepared.
If you're religious remember that god loves you and your child no matter what and if they are gay they will still be accepted by god.
I have a nephew who is gay and he came out to me first about it and I responded with love, care and compassion.
If you don't like your child being gay then don't come out yelling at them because that will do nothing to change the fact that they are gay.
Being gay is not a choice and is something that a child is born with so no matter what you do the child will always be gay.
You should then let them know that you still love them but need time to process the fact that they told you they were gay.
They are coming out to you because they feel they are loved and that they can trust you.
Yelling at them or trying to stop them from being gay will make the situation worse.