“…There are also "child" factors that have been shown to relate to vocabulary development. It has been frequently reported that girls outperform boys under 4 years of age (Harrison & McLeod, 2010;Reilly et al, 2009;Skeat et al, 2010;Zambrana, Pons, Eadie, & Ystrom, 2014) and girls and boys respond differently to known risks such as SES and parental input (Bornstein et al, 2004;Zambrana et al, 2014) whereas other studies have found no gender-based differences (Jackson, Schatschneider, & Leacox, 2014). Other child factors that have been found to be related to the acquisition of words are low birth weight (Leijon, Ingemansson, Nelson, Wadsby, & Samuelsson, 2016;Taylor et al, 2013), children's behaviour, and non-verbal cognitive skills (Beitchman et al, 2008;Law et al, 2012).…”