numPed(pedigree, check = TRUE)
Individuals must appear in the ID column in rows preceeding where they appear in either the Dam or Sire column. If check = FALSE
any pedigree will be transformed into a pedigree consisting of integers and missing values denoted by '-998'. CAUTION: this should not be set to TRUE without careful thought.
Based on code from the MCMCglmm
package
MCMCglmm