I think it ' s 1 . 5 <| sep |> I prefer the look of no wires showing . <| sep |> Medical Student Herethe reason why we have morhphological changes between people is mainly due to differences in hormone balances , there are numerous hormone regulation systems , some that increase while others that decrease hormones and some hormones affecting others releaseproduction . For example pregnant females have progesterone and prolactin increases that result in expanded mammalary glands that result in bigger boobs . If we take a step back we then evaluate how different proteins and cellular functions lead to these hormones being generated and regulated and what controls these proteins ? It is due to genetics and gene expression . TLDRhormones alter development , genes control those hormones .