Board Thread:Boruto Discussions/@comment-31080833-20170118090613

In another post I have made recently, I linked screenshots of the Boruto manga, in which Shinki refers to Gaara as "our great father", and then "foster father". It is safe to assume that Araya, Yodo, and Shinki are all Gaara's wards/foster children - Gaara likely took in the three of them so appease the council because he never married/had children, and neither did his elder brother, Kankuro.

Gaara's Inifnite Tsukuyomi showed his intense desire to have had a happy childhood, with his family, so he likely didn't foster one child in fear they would be lonely, so he took in three. This repeats the 'two brothers, one sister' theme for the Sunagakure family. Gaara's second reason behind foster more than one child is likely so he has more than one heir (on the off-chance the first one he chose died for any reason).

This does, indeed, make Shinki, Araya, and Yodo the "cousins" of Nara Shikadai, being they refer to Gaara as their guardian. 