Hope this helps: KINSHIP CHART in Help / Advice Posted February 21, 2016 · Report reply My grandfather and her grandfather are brothers. So that makes my father and her father first cousins and us 2nd cousins? Does it matter if we are both from the same side of the family with same last name even though we are 2nd cousins? Genetic wise 2nd cousins should hold lesser risk? Please advise, thanks!