Your grandparent's siblings are your grand aunts and grand uncles. Their parents are your great aunts and great uncles. I didn't know that until recently... called my grand aunts and grand uncles great aunts and uncles most of my life. I might have that wrong. Maybe it's your grandparent's aunts and uncles that are your great aunts and uncles. I was also told that my 1st cousin's kids were my second cousins. They're your 1st cousin once removed. PSC PPSCC PPPSCCC is the key to 1st, 2nd, and 3rd cousins. Your parent's parent's siblings child's child is your 2nd cousin.