I'm a male software engineer and I'm marrying a male software engineer, that may account for some the data too.
edit just to clarify, for men. Dating pool for homosexual/heterosexual men.
That's what i thought as well, from anecdata it seems to me the overwhelming majority of females and gay males in software development or IT live with males or females from the same industry.
I wonder if one day the industry is more evenly distributed if we'd see a similar percentage as for lawyers.