The picture is of Warren Jeff's who is NOT LDS or Mormon. He is no related to the church, and he is a polygamist of notoriety.
At one point the church practiced polygamy, in an effort to make sure that each home had a member of the priesthood in it, and that every woman and child had a father figure. It was also a commandment from God.
Why? Nobody really knows, some think it may have to do with the Lord's desire to have a large number of second and third generation members of the faith. It shouldn't be such a stretch though, I myself am quite happy with only one wife, and think even one is rough sometimes lol - but in the old testament it does speak of the patriarchs of old having plural marriages.
Polygamy is of course a practice that many in and out of the church didn't agree with, and those who did practice it had to be called by the church to fulfill that position.
Gordon B Hinckley has said many times that polygamy is not something the church endorses any longer, that there was a time and a place for it, but that that time is long past, and anyone who commits it is committing sin against the church.
One of our core beliefs is that we believe in obeying, honoring, and sustaining the law of the land. This means if polygamy is outlawed we obey that law. In 1904 polygamy wasn't just banned in the church in America, but in every land regardless of their laws.
President Hinckley made the following statement:
“I wish to state categorically that this Church has nothing whatever to do with those practicing polygamy. They are not members of this Church. Most of them have never been members. They are in violation of the civil law. They know they are in violation of the law. They are subject to its penalties. The Church, of course, has no jurisdiction whatever in this matter.
“If any of our members are found to be practicing plural marriage, they are excommunicated, the most serious penalty the Church can impose. Not only are those so involved in direct violation of the civil law, they are in violation of the law of this Church.” Polygamy is also not allowed within the Church even in countries where it is allowed. The Church today teaches that marriage is strictly monogamous and no one can be a member of the Church and practice plural marriage.
As you can see Polygamy is not a mormon thing any longer. We are no way related to the FLDS church, or other's like it and it is quite distressing when someone who is misinformed professes their total ignorance by claiming things they don't even know about.
Now you can be sure your facts are straight, and won't act the fool the next time you talk to your Mormon friends....