'How come...'

[Doni]

How come people say 'how come' instead of 'why'?

[BenDToy]

May be short for "How does it come about ......"?

[Quizmonster]

The phrase originated in the USA in the 1840s and means exactly what BenDToy suggests above. The past tense form existed in English usage for centuries before that, as in: "How came it that he married her?" The first use of the simple 'how come' did not appear here until the 1930s.

[Gef]

In the west of scotland it's just "how".