Schematic design of construction of genotypes. Triplets of genotypes with three levels of inbreeding were obtained using isogenic lines. Outbred genotypes (F~0) were obtained by crossing two isogenic lines (F~0.89). Male offspring from such crosses were crossed to females from the maternal isogenic line. Offspring from this cross inherited a haploid maternal genome from their mother and a haploid genome from their father, of which half came from the maternal line. Theses individuals were therefore homozygous for approximately 44.5% of their genome. Inbred genotypes came from maternal within-line crosses. With this design, genotypes of three levels of inbreeding produced by each pair of isogenic lines shared the same maternal genome, controlling for maternal effects variation among genotypes within a line-pair.