it is commonly assumed that the quantitative trait are distributed as normals.However
as Luo & Woolliams have pointed
this assumption is not reasonable in practice
which will lead to bias of the corresponding estimators.They also have suggested that the lognormal distribution of quantitative trait would be more reasonable.In this paper
under the assumption of lognormal distributed quantitative trait
we follow two estimating methodologies proposed by Luo and Woolliams: moment estimate and maximum likelihood estimate based on EM algorithm to estimate parameters.