nested random effects
An interaction random effect/fixed effect is noted as random ~1|random/fixed in your case random =~1|ID/FAM (but I don't uderstand why indiviuals withing families are fixed and and families are random, but there you go).
1. Fixed effects cannot be nested within random effects. 2. The "random" specification is backwards: nesting, |g1/g2/g3... , is outer to inner and so FAM/ID
Check out Pinheiro and Bates Ch1, especially pg 23 onwards.
Indeed. See the Worker/Machine example on p. 24 for outer to inner nesting. -- Bert Gunter