I don't think she has nits, I think she probably suffers from itchy dry scalp because she has eczema and since nits like clean hair I can't see Mark getting nits! It could also be a reaction to the shampoo she's paid to advertise to thicken her hair! Great ad! Although we saw from her recent Amazon shop she uses other shampoo now.
Also edited to say it doesn't seem they ever change their green leafy bedsheets/duvet which also won't be good for their asthma and eczema.
she has had nits many times as in the early days of Nadia & Kaye she spoke about - Maddie & Kiki passed them onto Kayes daughters as they did a live link to LS about it - Kaye was delicing her daughter! Nadia probably never does a thorough job of getting rid of them becuase shes so slap dash