According to one survey, farmers, fishermen, and lawyers, are the professions that are most likely to see intermarriage in the profession.
That is, farmers are likely to marry another person from a farm family, lawyers are likely to marry another lawyer, etc. Not that they all do, by any means, but they do so more than, say, accountants marrying another accountant.
Makes sense for farmers, I think. Fishermen and lawyers surprises me, however.