[mushaboom]

I'm writing a lab report about a free radical chain mechanism where dibromine is cleaved homolytically by light. I need to explain why homolytic cleavage occurs as opposed to heterolytic. The only thing I can think of is that both of the atoms on the bond are the same in electronegativity, so they should "share" the electrons equally. Are there other reasons as to why this is?

[AlphaScent]

This is due to a general tendency of the bond itself, If I remember correctly.  The bromine-bromine bond is weak when compared to other bonds, carbon-carbon for example.  The ability for the molecule to under go homolysis comes from the fact that the bond dissociation energy is low for that particular phenomena.