My culture uses 0-based ages, where in your first year on earth you are 0 years old and turn 1 after you have been alive for an entire year, but I am not sure age would be any more confusing if it were 1-based. I don't see anything fundamental there. Other cultures do use 1-based ages (you are 1 on the day you are born) and they seem to get along just fine. Whatever you are accustomed to is what seems natural.