Sorry to disagree with you.

Yes we are born of God. But to say that no matter what, after you become a Christian you are going to Heaven. So, people who backslide and walk away from God are still saved when their choice is clear they are rejecting God. That is careless and not provable.

Hebrews 2:1 Therefore we ought to give the more earnest heed to the things which we have heard, lest at any time we should let them slip.
2 For if the word spoken by angels was stedfast, and every transgression and disobedience received a just recompence of reward;
3 How shall we escape, if we neglect so great salvation...

"Giving heed" "Let them slip" "every transgression...received a just...reward" "how shall we escape if we neglect so great salvation" don't sound like once saved always saved.

1 Corinthians 9:27 But I keep under my body, and bring it into subjection: lest that by any means, when I have preached to others, I myself should be a castaway.

This doesn't sound like once saved always saved either.

There are more. Your analogy with your father and your family doesn't answer what these verses teach. We can disagree on what they mean, but I believe it is clear that even though we are saved by grace through faith in the finished work of Jesus Christ on the cross and Him rising from the dead, we can reject it later in life if we so choose. I agree that isn't always probable, but I've seen it happen. To say they were never saved in the first place is a cop-out. To say they are going to heaven after they have openly rejected Christ after being a Christian is careless.