Ok, so, i've always kissed my parents on the lips and they've always been fine with it. I've never felt weird about it until earlier today when i went to kiss my father and he leaned into my kiss. I dont want to make any accusations, but it felt kind of weird. He's never done that before. He also put his hand behind my head, (something he's done ever since i can remember), but this time it was different. It was almost forceful. Please help me. This isn't a joke.

As for your situation... It is odd he did this so I would recommend just not kissing him anymore if you feel uncomfortable with it.
I can't answer for Ur dad but maybe his thoughts are running different, I should talk to him about it and express to him how it made U feel. And stop kissing them on the lips, PLEASE!
No... I don't personally kiss my parents on the lips (not really at all anymore) but if your comfortable with it then whatever. It's your family.
It's strange that one time your Dad apparently did something different than usual but it may have just been wrongly interpreted or perhaps he accidently kissed you in a more sexual way than he intended(as weird as that sounds). He could even be embarrassed about it himself.
Listen, if it carries on then stop kissing your dad... if it goes further call child protection (I imagine you're still a child).
Don't let these narrow minded, insensitive, ignorant fools above me (excluding the ones not being that way of course) influence the way you show affection towards your family but don't let your Dad abuse you. Seriously.
Do not shrug away from your folks because of your own hang ups or is it desire?????
I think it's gross as well! I haven't kissed my parents since I was extremely young. And for him to get so into it...? OMG I think I just puked in my mouth!
its going to be abnormal if u see ur dad gets erection while kissing u