It is strained to you because you read a text translated into a different language describing events happening in a culture very distant from yours, but you imagine that you get the "clear meaning". This is why patristic tradition of interpretation is important, -- because they did not have the same linguistic and cultural barriers you have. Even the modern Greeks who read the Greek scripture today do not find it at all strained, as they continue to have big families where everybody but a stray dog is an "adelphos".
Was Lot Abraham's brother?
Was Elisabeth Mary's cousin?