Combined Unusual Genetic Attributes in Humans

This question is just out of curiosity.  Does anyone know if it is usual for a person who has one unusual physical feature to have several?  I am asking because I came across some information about the palmaris longus muscle, on Facebook, which I lack and supposedly this is unusual.  I then got to thinking that I also have B- blood type (1.5%) of people, I had two extra teeth that were removed in childhood (hyperdontia supposedly unusual to have more than one and not have an accompanying syndrome), I have an extra rib,  and I have a couple other abilities/attributes that are found in only 1-2% of the population.  Do these things usually cluster in some people or should I start believing some of the silly things that I have found on the internet about being a descendant of extraterrestrials? LOL