Ducklings - two males, one female?

[DukesDucks]

These Muscovy ducklings are about 2 months old. I'm thinking the two white ones are male, and the darker one a female. Darker one feathered out much earlier, and although hard to tell in pics, the white ones are now a little larger.

 

[DogIsMyShepherd]

With my muscovies I was able to tell by the size of their feet and legs. The males feet were bigger and legs thicker.