Xenophobia
There has been a lot of suspicion and negative attention turned towards immigrants lately. This is not new. From the beginnings of humanity, people have had a tendency to initially mistrust those who approach from outside the known tribe. There is even a term for this: xenophobia - the mistrust towards strangers. When we are approached by someone with a different look, culture, or mannerism; we feel uncertain and out of our depth. We don't know if they will react to us in expected ways, take offense when we mean no harm, or have the same moral structure as ourselves. Usually, a bit of conversation, good will on both sides, and a little time to get to know each other reduces and eventually eliminates the xenophobia and that which was "other" becomes understood and accepted, or at least tolerated.
However, when people are deliberately misled by people they should be able to trust (the media, politicians, authority figures) the fear can blow out of all proportion and lead to rejection and revulsion. In this day and age, there is no good excise for this. We now know that all of us come from the same roots. We are all the descendants of a handful of early mothers and fathers; and our very lives and societal mores are built on the foundations of our ancestors. If we take a moment to ponder our history we can see that xenophobia has no place in our world today.