U wat? Ur mother married your fathers brother, and she happens to be their cousin anyway?
On topic, parents can give their children either one's name, or both, like <father's>-<mothers>. If it happens that you don't like your name you can legally chance it for free for the first time (the second isn't free anymore).
Most Finnish names end -nen (case you haven't noticed), which actulally means 'little', as a postfix. For example, 'a little house' is 'pieni talo' but also 'talonen'. Some names are also other nowns, like 'grove' ('Lehto') or 'rock's stream' (Stenström (swe)=Kivenvirta (fin)). Some names come from Swedish, like Rosberg ('Rose Mountain').
But, as time goes names change. For example, Räikkönen, Kovalainen and Hynninen (that's me) don't mean anything, allthough Kovalainen in bits: Kova=Hard, (yes, I remember How Clarkson made fun of him. Irony eh) so it could be translated in many ways, for example 'Little Boner'. Not word to word, but with imagination...