Why would he lie about how many kids he has ?

If a guy lie to you about that is because maybe he fears that if you know about that you wouldn't date him or seem him. However I will give you this advice "when men lied once they lie again" if you know that he lied to you about that u should not maintain any kind of relationship with him any more not even as a friend because if you liked him and he gets to be ur friend you will fall for him again.