The Bagua forms a perfect Chinese family. Father, mother and their three sons and three daughters. In marriage, it is also preferred to have the oldest daughter matches the oldest son and youngest daughter matches the youngest son. This has been a well respected tradition in the "good old days" of arranged marriage. Today, most people no longer bother with such "nonsense". 

Gua  Family member
kun 000Kun (000) mother
zhen 001Zhen (001) the first son, the older male
Li 101Kan (010) middle son
dui 011Dui (011) small daughter, younger female
gen 100Gen (100) small son, younger male
Li 101 Li (101) middle daughter
xun 110Xun (110) the first daughter, older female
qian 111Qian (111) father