Weight loss, pregnancy, ageing… with some of life’s changes, you can guarantee that some silvery purple lines might start sprouting over your skin. But why do some people get them, and others walk away stretch mark free? According to research published in the Journal of Investigative Dermatology, genetics are one of the main determining factors in whether or not you’ll get stretch marks. During the study, scientists from the personal genetics company 23andMe examined the DNA of 33,930 people. Of these participants, 4,967 were women with severe pregnancy-related stretch marks. The study found that mutations in four specific genes groups - ELN, SRPX, HMCN1, and TMEM18—increased the participants’ risk of developing stretch marks by 40%. Of these genes, the ELN (elastin) was the closest tied to stretch marks, with those developing stretch marks most notably having mutations to their ELN gene in their DNA. In the study, only 25% of the men reported having stretch marks, rather than the 55% of women who answered the survey. The women were also reported to have higher mutations of their ELN gene in their DNA. Stretch marks are known to be caused by excess tension on the elasticity of the skin, yet the study author Joyce Tung said the new genetic discovery shows a direct link between your DNA and your skin’s ability to ‘bounce back’: “Previously, no genetic variants were known to be associated with isolated stretch marks.” So, while you may look to reduce the visible effects of stretch marks, unfortunately it’s down to the genes under the jeans for just how visible they’re going to be.