Today I took DS1 (8) for a consultation to have orthotropic braces to correct overcrowded teeth.
What was very interesting was at the end of the consultation, the dentist looked at me and said "You used to suck your thumb, didn't you?". We'd talked a little about family teeth (orthodontics, extractions etc of which I've had none) but I'd not mentioned my thumb sucking which I must have done until 8 or 9 I guess. My teeth are a little overcrowded but fairly straight, no overbite, underbite or anything like that and this dentist had not looked in my mouth at all. He was absolutely right. Whilst the teeth may be straight, it will (apparently!) be because the jaws have grown differently to compensate.
So, you may claim tht thunb sucking hasn't affected your teeth at all but you are in all likelihood wrong Whilst I've always been adamant that thubb sucking had affected DSs teeth I was just as sure it hadn't afected mine.