“…First, parental characteristics include demographic variables such as age (Zuo et al, 2011), participation in social insurance (Ning et al, 2019), income and property (Kalbarczyk-Steclik & Nicinska, 2012;Wu & Li, 2014), investment in children (Cunningham et al, 2013), guardianship of grandchildren (Lin & Pei, 2016), and residence with children (Chen et al, 2017). Second, children's characteristics include gender (Gruijters, 2018;Lei, 2013), education level (Pei & Cong, 2018), work status (Cong & Silverstein, 2011), income (Park, 2014), filial piety (Lin & Yi, 2011;Silverstein et al, 2006), and parent-child relationships (Zhu, 2016).…”