They look part alba because they all are which is the entire point @Richard was making
"Differentiating mulberry species and varieties can be challenging. Mulberry varieties easily hybridize making it very difficult to know exactly what species you have. Plants that are easy to propagate such as figs, guavas, dragonfruit, and mulberries also lose distinct identification as cuttings are passed around; I can’t tell you how often I hear “I forget which one this was!” Understanding why this is important will become clearer as we get into specifics.
To briefly get into the weeds- or the trees for that matter, the genus classification is quite complicated due to various geographically isolated and genetically distinct strains, and an extreme propensity for hybridization among most varieties. Some taxonomists include as many as 200 distinct species, but only about 10-17 are officially recognized, and even those do not necessarily have clear genetic origins. "