How were farmers able to obtain present day cabbage, cauliflower and broccoli from wild cabbage?

Explanation

Humans cultivated wild cabbage as a food plant, and generated different vegetables from it by selection:
• In order to maximize the amount of food they got from it, they planted seeds from plants that grew more leaves, and after many generations, produced a larger leafy version of wild mustard called as kale or collard greens.
• Later farmers wanted very short distances between leaves. Hence they selected the variants of the plant that produced enlarged leaf buds in particular. After many generations, this led to plants with huge heads of tightly rolled leaves that we would call cabbage.
• Elsewhere, farmers selected for enlarged flowering structures (creating broccoli for arrested flower development and cauliflower for sterile flowers)
• Swollen and enlarged stems (kohlrabi),
• Many small heads (brussels sprouts).