At times, it can be easy to forget that the core gang of How I Met Your Mother even have families - after all, they spend every major special occasion and life event with each other! However, over the course of the show, fans do get to meet most of the parents and siblings of the main characters, although some definitely appear more than others.
Lily's Mom, for example, barely makes an appearance, and her grandparents basically just show up to give her a house. Ted's Dad, too, only pops in for a couple of punchlines, and Barney has a half-sister who is in only one episode (and doesn't even seem to be at his wedding). But of the relatives that actually get some development on the show, who are the ones fans would love to have in the family... and who would be the absolute worst?
Best: Ted's Mom Virginia
Ted's Mom may not be perfect, and her new husband Clint is definitely quirky (and of course, Ted hates that), but Virginia Mosby is quite simply adorable. She and her ex-husband seem to still get along (he goes fishing with Clint), she gets along with the gang (Lily even calls her up when Ted calls her a 'grinch'), and she is head over heels for Clint, which is a pleasure to see. She gets giggly and excited over love, and only wants the best for her son, too.
Worst: Barney's Dad Jerome
Fans have a certain amount of sympathy for Jerome - but far more for Barney. When Barney was a kid, his father showed up from time to time as an 'uncle', but he was rarely around, and never told Barney the truth. Later, when he got his act together, he started a new family - and Barney was left to spend his life wondering who his dad was (and thinking it was Bob Barker), and struggling with abandonment issues. When they did finally reconnect, it led to one of the most emotional moments in the show, as Barney broke down, asking why, if Jerome was just going to be a suburban Dad, he couldn't have been that for Barney.
Best: Robin's Sister Katie
At first, Robin's sister Katie seems like an awful, rebellious teenager. She has come to visit with her boyfriend, is smoking and drinking, and is planning on having sex, which shocks Robin (who still sees her as a little girl). The sisters have a fight, and it seems like everything is going wrong with the visit - until Katie's boyfriend dumps her, and she turns to her sister for comfort. It becomes clear that she's just a good kid trying to pretend she is older and cooler than her age, and she's a sweet young woman at heart.
Worst: Marshall's Brothers
Not a lot is seen of Marshall's brothers, and Marshall definitely loves them, but what fans do see is a bit worrying. They are constantly making fun of Marshall, and picking on him - and it's even revealed that they had shockingly violent 'fight clubs' when they were teenagers.
At times, they seem like decent suburban adults, but at other times, they regress, and bully Marshall mercilessly. It's just childish and mean.
Best: Barney's Mom Loretta
Loretta is definitely an interesting woman - and she's led quite the life. When Barney and his brother were younger, Loretta may not have been the best mother, in her own words, she was "a wh*re, dear", and her casual references to her past sexcapades definitely made the gang a little uncomfortable at times. However, she comes into the show as a lovely older woman who is doing her best - and she was always trying to be a good mom to the boys. She makes sloppy joes, she pretends to love Barney's fake family even though she can't stand them, she helps out with the gang... she has her flaws, no doubt (and a tendency to lie about everything!), but it all comes from a place of love, and wanting the best for her boys.
Worst: Lily's Dad Mickey
While Lily is able to reconcile with her father by the end of the show, there's little doubt that he's a pretty awful father for most of her life. Her stories include him missing her recitals and big events, using money for her braces to try and sell his next big idea for a board game, and generally never being there for her because he is always too busy pursuing his board game dreams. He never helped support the family, and even moved back in with his parents in middle age, forcing them out of retirement to support him. He ruined Lily's dinner parties and was generally crude and selfish - but eventually, they started to sort their relationship out.
Best: Barney's Brother James
James isn't just one of the best relatives, but one of the best characters on the show! Barney's brother manages to be just as fun and 'cool' as Barney, without all the womanizing ways. In fact, when he is first introduced to the show, he is about to get engaged to his boyfriend.
The two later get married and have two children, and James is always charming, funny, and a great addition to any episode. He's not perfect, and does later cheat on his husband (although the two manage to move past it), but he's definitely one of the best-liked secondary characters on the show.
Worst: Ted's Sister Heather
Heather and Ted have a strained relationship, and it's easy to see why - as Heather is something of a wild child. As Ted says "it took her six years to graduate from three different colleges, during which time she wrecked two cars, got married for five days, and lived in a tree for nine weeks, only to realize that no one had any intention of cutting it down.". She had previously stolen his furniture and TV to buy plane tickets to go to a NIN concert, and was later caught shoplifting. She claims that by the time of her appearance, she has grown up, and wants to prove to Ted that she is serious about starting a career in finance... which she does by trying to lie and manipulate her brother into thinking she had sex with Barney in his office. She may be maturing, but this is not the behavior of a mature woman.
Best: Marshall's Parents
Marshall's parents are an absolutely adorable couple, and incredibly good parents to Marshall, too. It's clear that he loves them and admires them, and he's enthusiastic about his family life in Minnesota (even if Lily is less so). His parents are also adorably outdated in a lot of ways, but this just makes them more charming, and they are incredibly supportive of Marshall. The moment that his father died is possibly the saddest in the entire show.
Worst: Robin's Parents
On the flip side, Robin's parents are in the running for worst sitcom Mom and Dad of all time. Robin's mother is essentially absent - and even refuses to come to her own daughter's wedding, which is heartbreaking. Her father is far more present, but he's much worse. He wanted to have a son, and raised Robin as a boy. On top of that, he raised her in a bizarre survivalist way, at one point pushing her out of a helicopter as a teen to survive in the woods, and making her hunt when she didn't want to. Later, he gets remarried without even telling her, and she nearly cut him out of her life. By the end, he is still a small part of Robin's life, but it's clear that they'll never be close.