I guess it depends how you think about altruism. Kin selection certainly means sacrificing our own wellbeing to benefit the wellbeing of our relatives, so in that sense you could call it altruistic. But given the clear benefits of this behavior for our own genes (because relatives share our genes), many would argue it’s not really altruistic at all.

Helping a complete stranger at a large personal cost — perhaps donating our kidney to them — is a less debatable altruistic act.