I would he just had Jonah and that was it since he always saw him and no other ones, so maybe he was trying to trick her into thinking that he had more then he really had.
The conversation between Sam and Victoria doesn't, at any point, suggest that Sam has multiple children. He simply asks Victoria, "Do you have kids?, to which she answers, "No.". His response, "Want mine?", is exactly the way he would respond whether he had 1 child or 12, but clearly we see through the movie to this point, that Sam and Jonah are the only two in the family. Just because he asked about "kids".. plural (which is typically the way people ask this question... or perhaps, Do you have ANY kids?) doesn't suggest he has multiple children. It surprised me to hear that people would perceive this dialogue that way.
Umm why is that disturbing???? He has one son, that’s all. Nothing weird or creepy about that at all, what’s the reasoning for the rediculous comment “we see no other kids” so what???