Girls, hello everyone! My son is 9 months old, he can only roll over a…

Girls, hello everyone! My son is 9 months old, he can only roll over and sit if you put him down. He doesn't sit on his own, let alone stand up. Even if you put him against a support, he won't stand. ? All the babies are already crawling, walking against a support, sitting, and we have nothing at all ? A neurologist said everything is normal. What do you think? Are there still such late babies?