B thunbergii has green foliage. It is B thunbergii 'Atropurpurea' and other red leaved cultivars that have the burgundy foliage. If you sow seeds of the coloured cultivars you will get a mix of leaf colours in the offspring but the majority will be coloured. So no, it would not be unusual.

Note that B thunbergii is listed as an invasive species in NC.

Berberis is extremely invasive in VA. When hiking I frequently see (and pull) young berberis plants. If a gardener wanted burgundy foliage there are better choices.

Yes - invasive in lots of places but I mentioned NC because that's where Logan-Caldwell is located. He has a penchant for propagating/recommending invasive species.

Ok, thanks for answering my question floral. I grew one for seed to use as an accent shrub at the end of my row of boxwood topiaries and it had (has) the beautiful red foliage. Will NEVER remove it. If it makes you feel any better, I only have this one and it isn't producing seed yet.