If this looks complicated, it isn't really. Everyone is walking with at least one step-something. Also, Wayne is married to Claudia's sister. That should be all you need to know to make sense of the chart:
Adam Thomson
16
Son of Richard, stepson of Claudia, stepbrother of Marty
Alexis Coppola
14
Stepdaughter of Wayne, cousin of Marty
Claudia Thomson
44
Wife of Richard, mother of Marty, stepmother of Adam, aunt of Alexis
Marty Boeker
17
Son of Claudia, stepson of Richard, cousin of Alexis
Richard Thomson
44
Husband of Claudia, father of Adam, stepfather of Marty, brother-in-law of Wayne
Wayne Munns
44
Stepfather of Alexis, brother-in-law of Richard and Claudia.