Pushing tongue against the front teeth in childhood often results in buck teeth. Some people do it as an adult as well.
It is not very rare to get buck teeth from thumb sucking, as thumb sucking is one of the most common childhood habits.
Excessive use of Pacifier puts the same pressure on a child’s developing jaw and teeth as thumb sucking does.
The alignment of the jaw and teeth get disturbed both by missing and crowded teeth, causing protruding teeth.
If your parents and other blood relatives have overjet teeth, you can also get the misaligned jaw and teeth in hereditary.