Complex sentence: My grandfather is half English as his father was an English soldier who helped with the liberation of the Netherlands so that means that I'm 12,5% English, and although that's not too much I'm proud of it.
Split into simpler sentences: My grandfather is half English because his father was an English soldier who helped with the liberation of the Netherlands. Therefore I am 12,5% English, and although that's not too much I'm proud of it.