Human penis size
It has been suggested that penis size differences between individuals may also be caused by environmental factors such as culture, diet, chemical/pollution exposure, etc. Endocrine disruptor resulting from chemical exposure has been linked to genital deformation in both sexes (among many other problems). Chemicals from both synthetic (e.g. pesticides, anti-bacterial Triclosan, plasticizers for plastics, etc.) and natural (e.g., chemicals found in tea tree oil and lavender oil) sources in the blood of pregnant women have been linked to various degrees of endocrine disruption.