Help with Chick down genetics

[3riverschick]

Hi, Can some expert out there help me please? I have chicks hatching. it's a Light Sussex ex cuckoo Marans pullets
They are sold. I have two colors of chicks: solid black ; and solid black with a white dot on the head. Can anybody help me with determining the sexes?
Thank you very much !
The yellow chicks are pure English strain Light Sussex chicks. No problems there.
Karen

 

[The Moonshiner]

Are you saying theyre a light sussex rooster x cuckoo marans hens offspring?
If so solid black are pullets and head spot blacks are cockerels.

 

[3riverschick]

Thanks Moonshiner. okay that means we've got five cockerels and two Pullets. now that's interesting what you said about the temperature because in that particular hatch of LS ex CM, we had five robust Cockerels and two delicate pullets. A third pullet was born immature physically and we had to cull it. so maybe the temperature was a little bit high for this particular cross?
the pure Light Sussex chicks hatched in the same tray came out just fine .no problem with them. Just nice robust chicks in both sexes.
Best ,
Karen