Earlobe shape is determined by genetic factors. There are two main types of earlobe shapes: free earlobes and attached earlobes. Free earlobes are those that are not attached to the side of the head, while attached earlobes are those that are fused to the side of the head.
The inheritance pattern of earlobe shape is autosomal dominant. This means that only one copy of the gene for free earlobes is needed to produce the free earlobe phenotype. Heterozygous individuals, who have one copy of the gene for free earlobes and one copy of the gene for attached earlobes, will have free earlobes. Homozygous individuals, who have two copies of the gene for free earlobes, will also have free earlobes. Homozygous individuals, who have two copies of the gene for attached earlobes, will have attached earlobes.
The frequency of free earlobes in the population is estimated to be around 60%. This means that approximately 40% of individuals have attached earlobes.