Relationship between parental consanguinity and digit ratios (2D:4D) among Turkish newborns in Sivas

Abstract

Objectives: The aim of this study was to investigate the effects of parental consanguinity on the 2D:4D digit ratio of newborn infants, whose parents were the first cousins. Methods:The study included healthy and full-term newborn infants, delivered in a hospital, at the gestational ages from 37 to 41 weeks. A total of 225 newborns and their parents were included in the study. Of these 225 newborns; 100 were inbred and 125 were outbred infants. We used a Vernier caliper to measure the length of the second and fourth digits of the newborns (accuracy: 0.01 mm). Results: Controlling for education and number of pregnancies, male newborns had lower digit ratios than female newborns, for both left and right hands. There were, moreover, differences between inbred and outbred samples. We determined that inbreeding was related to a reduction in the digit ratios regardless of the side of the hand and the sex of the infant, showing a consistent tendency to appear more masculine. Interaction between marriage type*sex was highly significant. Conclusions: Parental consanguinity appears to cause fetal masculinization of digit ratios by increasing fetal stress among Turkish newborns.

The relationship between mothers' second and fourth finger lengths (2D:4D) and anthropometric measurements (height, weight, head circumference, and 2D:4D) of the newborns

“…Studies found in literature have shown that adult women's 2D:4D ratio is higher than adult men's 2D:4D ratio (Malas et al, 2006; Manning et al, 1998; Robinson & Manning, 2000). At the same time, 2D:4D ratio of female newborns was also found to be higher than that of male newborns (Ertuğrul & Özener, 2020; Ventura et al, 2013). However, Ventura et al (2013) did not confirm this for left hand.…”

“…Studies conducted so far have been conducted on 2D and 4D measurements of only adults or children or only on 2D and 4D measurements of newborns (Brown et al, 2002; Ertuğrul & Özener, 2020; Garn et al, 1975; Malas et al, 2006; Manning et al, 1998, 2005; Öztaşan & Kutlu, 2014; Phelps, 1952; Robinson & Manning, 2000). In fact, the number of studies on newborns is limited (Ertuğrul & Özener, 2020; Ventura et al, 2013). Almost all studies comparing mothers and newborns have been done at the hormonal level (Brown et al, 2002; Galis et al, 2010; Manning et al, 1998; Phelps, 1952; Robinson & Manning, 2000).…”

“…There are only a few studies conducted on the measurement of finger length in the early stages of newborn infants. These studies show that newborn males have lower 2D:4D ratio when compared with newborn females (Ertuğrul & Özener, 2020; Ventura et al, 2013). There are also studies which have found that newborns have lower 2D:4D ratios than adults (Galis et al, 2010; Knickmeyer et al, 2011; McIntyre & Alexander, 2011).…”

2D:4D ratio as marker of prenatal androgenization and its predictor validity for anthropologists and evolutionary psychologists: “pro” and “contra”

“…Ïðè ýòîì, aeåíùèíû ñ áîëåå íèçêèì ïîêàçàòåëåì 2D:4D èíäåêñîì èìåëè áîëüøå øàíñîâ ðîäèòü ìàëü÷èêîâ ïî ñðàâíåíèþ ñ aeåíùèíàìè ñ áîëåå ôåìèíèííûì ñîîòíîøåíèåì. Òóðåöêèå äàííûå ïðîäåìîíñòðèðîâàëè, ÷òî èíáðèäèíã (ðîäèòåëè ÿâëÿëèñü äâîþðîäíûìè áðàòüÿìèñåñòðàìè) ìîaeåò ñóùåñòâåííî ïîâûøàòü ýìáðèîíàëüíûé ñòðåññ è ñïîñîáñòâîâàòü âíóòðèóòðîáíîé ìàñêóëèíèçàöèè [Ertugrul, Ozener, 2019].…”

The relationship between offspring's 2D:4D ratio and postpartum maternal circulating testosterone, estradiol, and their indices in a Ghanaian population

“…However, the association between the 2D:4D ratio and prenatal testosterone (PT) and estrogen (PE) exposure was not predicted until the publication of Manning (Manning et al, 1998). It was observed that high PT exposure leads to lower digit ratios and vice versa, such that the average male has lower digit ratios as compared to the average female in many populations (Butovskaya et al, 2021; Ertuğrul & Özener, 2020; Williams et al, 2000).…”