Pronunciation tendencies
I tend to think there is more to this problem than tendencies. It has been shown often that children up to a certain age are capable of learning to speak another language with native fluency and without any accent. But at some point, usually the teens, if they learn a new language they may learn to understand and write with native fluency, but will always speak it with some degree of an accent. The older you are when you learn a language, the heavier your accent will be. Thus, it would seem that our vocal apparatus is conditioned from birth to our native tongue and unless a new language is learned early, it will not adapt to another. A case in point is French speakers. The most obvious trait of someone speaking English with a French accent is the inability to pronounce the "th" sound, which does not exist in French; or the inability of English speakers to pronounce the French 'u' or German 'ü' which does not exist in English.