{"id":58472,"date":"2011-12-24T13:28:27","date_gmt":"2011-12-24T21:28:27","guid":{"rendered":"http:\/\/blogs.discovermagazine.com\/gnxp\/?p=14977"},"modified":"2011-12-24T13:28:27","modified_gmt":"2011-12-24T21:28:27","slug":"how-much-do-siblings-differ-in-height","status":"publish","type":"post","link":"https:\/\/www.razib.com\/wordpress\/2011\/12\/24\/how-much-do-siblings-differ-in-height\/","title":{"rendered":"How much do siblings differ in height?"},"content":{"rendered":"<p>In the comments below <a href=\"http:\/\/blogs.discovermagazine.com\/gnxp\/2011\/12\/a-mediocre-mans-great-son-a-great-mans-mediocre-son\/comment-page-1\/#comment-109723\">a reader<\/a> asks about the empirical difference in heights between siblings. I went looking&#8230;and I have to say that the data isn&#8217;t that easy to find, people are more interested in the deeper inferences on can make from the resemblances than the descriptive first-order data itself. But here&#8217;s <a href=\"http:\/\/books.google.com\/books?id=2KrTtoozuzgC&#038;pg=PT16&#038;%23038;lpg=PT16&#038;%23038;dq=average+difference+height+sibling&#038;%23038;source=bl&#038;%23038;ots=JMMpJFI1YS&#038;%23038;sig=ywPVihE28jthPNOSqHIE67BTw1o&#038;%23038;hl=en&#038;%23038;sa=X&#038;%23038;ei=HDv2TuRBx9qJArGFqaQO&#038;%23038;ved=0CHMQ6AEwCQ%23v=onepage&#038;%23038;q&#038;%23038;f=false\">one source<\/a> I found:<\/p>\n<hr\/>\n<table border=\"1\" width=\"550\" padding=\"5\">\n<tbody>\n<tr>\n<td><strong><em>Average difference<\/em><\/strong><\/td>\n<td><strong>Identical twins<\/strong><\/td>\n<td><strong>Identical twins raised apart<\/strong><\/td>\n<td><strong>Full siblings<\/strong><\/td>\n<\/tr>\n<tr>\n<td><strong>Height, inches<\/strong><\/td>\n<td>0.67<\/td>\n<td>0.71<\/td>\n<td>1.8<\/td>\n<\/tr>\n<tr>\n<td><strong>Weight, pounds<\/strong><\/td>\n<td>4.2<\/td>\n<td>9.9<\/td>\n<td>10.4<\/td>\n<\/tr>\n<tr>\n<td><strong>IQ<\/strong><\/td>\n<td>5.9<\/td>\n<td>8.2<\/td>\n<td>9.8<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<hr\/>\n<p>These data indicate that IQ and height variation among sibling cohorts is on the order of ~2\/3rd to 3\/4th of the variation that one can find within the general population (my estimate of standard deviation of 2.5 inches for height below is about right, if a slight underestimate according to the latest data). But I also found a <a href=\"https:\/\/vpn.lib.ucdavis.edu\/ejhg\/journal\/v16\/n4\/full\/,DanaInfo=www.nature.com+5201992a.html\">paper with more detailed statistics<\/a>.<\/p>\n<p><span id=\"more-14977\"><\/span><br \/>\n<a href=\"http:\/\/blogs.discovermagazine.com\/gnxp\/files\/2011\/12\/5201992f2.gif\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/blogs.discovermagazine.com\/gnxp\/files\/2011\/12\/5201992f2-300x256.gif\" alt=\"\" title=\"5201992f2\" width=\"300\" height=\"256\" class=\"alignleft size-medium wp-image-14978\" \/><\/a>The aim of the paper was to find outliers from expectation. In other words, <b>which siblings diverged <i>a lot<\/i> from what you&#8217;d expect in terms of normal variation within the cohort?<\/b> In the process they do report some statistics on inter-sibling variation. The correlation of height between siblings after correcting for age and sex are 0.43. This is what I&#8217;ve seen in the literature. Next, the standard deviation is 6.7 centimeters. This is about ~2.7 inches. The average phenotypic difference between siblings was about 7.2 centimeters (<i>D<\/i>). Therefore, to a first approximation the recapitulation of population-wide variation in a continuous quantitative trait within sibling cohorts seems to hold. Though I&#8217;d be curious if readers can provide better and more diverse sources.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/feeds.feedburner.com\/~r\/GeneExpressionBlog\/~4\/m4mRb7lu-Cg\" height=\"1\" width=\"1\"\/><\/p>\n","protected":false},"excerpt":{"rendered":"<p>In the comments below a reader asks about the empirical difference in heights between siblings. I went looking&#8230;and I have to say that the data isn&#8217;t that easy to find, people are more interested in the deeper inferences on can make from the resemblances than the descriptive first-order data itself. But here&#8217;s one source I [&#8230;]<\/p>\n","protected":false},"author":12,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[508,509,1911],"tags":[],"class_list":["post-58472","post","type-post","status-publish","format-standard","hentry","category-height","category-quantitative-genetics","category-variation-in-siblings"],"_links":{"self":[{"href":"https:\/\/www.razib.com\/wordpress\/wp-json\/wp\/v2\/posts\/58472","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.razib.com\/wordpress\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.razib.com\/wordpress\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.razib.com\/wordpress\/wp-json\/wp\/v2\/users\/12"}],"replies":[{"embeddable":true,"href":"https:\/\/www.razib.com\/wordpress\/wp-json\/wp\/v2\/comments?post=58472"}],"version-history":[{"count":1,"href":"https:\/\/www.razib.com\/wordpress\/wp-json\/wp\/v2\/posts\/58472\/revisions"}],"predecessor-version":[{"id":58827,"href":"https:\/\/www.razib.com\/wordpress\/wp-json\/wp\/v2\/posts\/58472\/revisions\/58827"}],"wp:attachment":[{"href":"https:\/\/www.razib.com\/wordpress\/wp-json\/wp\/v2\/media?parent=58472"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.razib.com\/wordpress\/wp-json\/wp\/v2\/categories?post=58472"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.razib.com\/wordpress\/wp-json\/wp\/v2\/tags?post=58472"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}