Sweet Peppers?

[growmore]

I usually just grow veggies as in Sprouts,cabbage,Caulis leeks,kale etc.But since seeing You all on here with the fancy bits I decided to have a go at Aubergines and peppers.
So I sowed a packet of sweet peppers red ,yellow, green, on packet.
All have grown and fruited ok.The question is one of the plants have got Black or very deep purple peppers on, they look shiny  and seem healthy etc.Is this a normal colour for sweet peppers..
They are growing this colour straight away as in  the little peppers on plant as well as big ones.
I have grown this  at the side of aubs could it be a sport or cross polination that has gone on .Or is this a natural colour for peppers..
I will post a pic if this is unusual..cheers ..Jim

[growmore]

[tim]

Peppers tend to go 'black' before they go red. Without seeing, don't know. = Tim

[feet of clay]

I've got dark purple/black ones too - on a couple of plants whilst the others are green.  Seem to think they were from a mixed pack of seed.  I grew black(ish) ones a couple of years ago, too.

[john_miller]

It's probably just genetic variation among an OP variety. One of the aims of F₁ hybridisation of peppers was to breed uniformly green peppers that would have more 'shelf appeal'.