A farmer has two homozygous varieties of tomatoes. One variety, called Little Pete, has fruits that average only 2 cm in diameter. The other variety, Big Boy, has fruits that average 14 cm in diameter. The farmer crosses Little Pete and Big Boy; he then intercrosses the F1 plants to produce F2 progeny. He grows 2000 F2 tomato plants and doesn't find any F2 offspring that produce fruits as small as Little Pete or as large as Big Boy. If we assume that the differences in the tomato size of these varieties are due to genes with equal and additive effects, what conclusion can we make about the minimum number of loci with pairs of alleles determining the differences in fruit size of the two varieties?