Now - normally, the copies of the genes contributed by the mother, or maternally derived genes, to this region, are silenced, or turned off, and only the genes from dad, or paternally-derived genes, get expressed.

正常情况下，这些基因若来自于母亲，也就是母源基因，那么这些基因就会被沉默或抑制表达，只有父源基因才会成功表达。