DavidWDavid W. Smith and M. Michael Cohen hypothesized the widow's peak hairline to be an anomaly<ref name=lancet>{{cite journal|title=Widow's Peak Scalp-Hair Anomaly and its Relation to Ocilar Hyperthelorism|author1=Smith, D.W.|author2=Cohen, M.M.|journal=The Lancet|volume=302|issue=7838|page=1127|date=November 17, 1973}}</ref> that results from a lower-than-usual point of intersection of the bilateral periorbital fields of hair-growth suppression on the forehead.<ref name=hall>{{cite book|title=Handbook of physical measurements|author1=Hall, Judith G.|author2=Allanson, Judith|author3=Gripp, Karen|author4=Slavotinek, Anne|publisher=Oxford medical publications|isbn=0-19-530149-8, 9780195301496|year=2007|page=336|url=http://books.google.com/?id=mmKNPQUZ8cwC&dq=Widow's+peak+scalp-hair+anomoly+and+its+relation+to+ocular+hypertelorism}}</ref> This can occur because the periorbital fields of hair-growth suppression are smaller than usual, or because they are more widely spaced.<ref name=hall/> Wide spacing also explains the association between [[human eye|ocular]] [[hypertelorism]] – that is, the eyes being abnormally far apart – and widow's peak;<ref name=hall/> this was suggested by findings in an unusual case of ocular hypertelorism in which surrounding scalp-hair growth was suppressed by an ectopic (displaced) eye.<ref name=lancet/> Widow's peaks are a symptom of [[Donnai-Barrow syndrome]], a rare genetic disorder caused by mutations in the [[LRP2]] gene.<ref>Donnai-Barrow syndrome, National Institute of Health, http://ghr.nlm.nih.gov/condition/donnai-barrow-syndrome</ref> Other genetic syndromes occasionally associated with widow's peaks include [[Waardenburg syndrome]] and [[Aarskog syndrome]].<ref>William Reardon (2008). "The Bedside Dysmorphologist". ''Oxford University''</ref>
A study of females conducted by Nusbaum and Fuentefria in 2009 found that 81% had a widow's peak.<ref>http://udel.edu/~mcdonald/mythwidowspeak.html</ref>
