First Time Pepper Grower Question (Jalapeno)

Hey all!

First timer here.

I grow other "stuff" and this was my first attempt at an outdoor vegetable garden.

Noticed that the peppers on one of my jalapeno plants is developing a purplish black streak that is spreading to the whole pepper.

Is this a genetic thing or some type of deficiency?

Any feedback or guidance would be great 🙏