R help - Nov 2007 - Fixed heritability in an lme model

Hi R help,

I wanted to set a fixed heritability for the object "Trait" left of ~
operator. Is this possible using lme, or would I need to use something
like gls?

This is the model line contained within a function;

lme.out <- summary(lme(Trait ~ genotype, random = ~1|sire,
weights=~number, na.action="na.omit")) 

Many thanks for any help.