Some people have attached earlobs and some people have three earlobs the difference in these traits are caused by what?
The presence of attached or free-hanging earlobes is predominantly determined by genetics. The trait is controlled by a single gene with two alleles, one for attached earlobes and one for free-hanging earlobes. If an individual inherits two copies of the allele for attached earlobes, they will have attached earlobes. If they inherit at least one copy of the allele for free-hanging earlobes, they will have free-hanging earlobes.
Similarly, the presence of three earlobes, also known as polydactyly, is also determined by genetics. Polydactyly is a rare trait that is usually inherited as a dominant trait, meaning it only takes one copy of the gene for an individual to exhibit the trait. If both parents carry the gene for polydactyly, their offspring may inherit the trait and have three earlobes.