Personalities are generally defined as the set of behaviours, characteristics, thoughts, attitude, habits & expressive patterns evolved from genetic and environmental factors.
A gene is the unit that is involved in transmitting characteristics from one generation to the next generation.
There are about 20,000 to 25,000 genes in the Human cell and we all have almost identical genes.
Personality is not determined by any of single genes, but relatively by the actions of numerous genes working together.
Yes, personalities are also inherited by our parents.