Realistically however, they can be the precise moment of eruption of a dormant family-volcano that's been brewing for a lifetime, and once you begin to hear the rumblings beneath the surface, you're looking at an inevitable seismic shift in kindred relations.
Which leads us to the predicament one woman has found herself in.
The bride-to-be, who uses the name PsychGirl13 on online wedding forum WeddingBee, took to the forum to ask about whether or not she should be expected to ask her sister to be part of her wedding after she "ruined" her proposal.
"I don't want my sister in my wedding party," declared the poster, before explaining the quandary she's found herself in in the lead up to her engagement.
"If we weren’t related, we wouldn’t even be friends"
"Basically, I’ve always felt that my sister is a narcissistic, conniving, and mean human being," she began her account, "we’ve never bonded as sisters. I’ve told my closest friends and boyfriend that if we weren’t related, we wouldn’t even be friends."
"My boyfriend of six years is planning on proposing soon," she wrote, and explained that her partner had come up with a plan to pop the question around the same time as the couple were planning to adopt a cat. Her sister overheard, and told the woman her boyfriends plan to propose.
With the cat out of the bag, so to speak, the boyfriend was forced to come up with another way to pop the question.
"My boyfriend doesn’t want her in our wedding party and now I’m contemplating the idea," the woman wrote. "She has already kinda ruined a proposal, so I can only imagine what it would be like to have her in my wedding. Should she be in my wedding party to keep family peace?
She brings out the absolute worst in me and when I’m with her, I feel like we’re teenagers fighting again. It’s so childish."
"Weddings bring out the worst in people"
"If you don’t get along with her, you shouldn’t need to have her in your wedding party," one poster responded, and said that as she and her siblings aren't 'close' they wouldn't be involved in her wedding, nor she in theirs.
Another user came down on the side of compromising for the great family good, saying, "I am all about keeping the peace, so I vote yes on putting her in the bridal party."
One poster came up with the solution to have the sister as a bridesmaid in name only, and avoiding giving her any 'duties' in both the lead up to, and on, the big day.
"Weddings bring out the worst in people," another poster declared and advised the bride-to-be to think of the future where "you will be kicking herself for not nipping this problem in the bud."
One woman shared her story of family bickering that lead her to scrap the idea of having her siblings involved in her wedding full stop.
"I was thinking of having them do readings or be involved in some other way, but after a major family blow up, they didn’t talk to me for months.
I decided to not have any readings just to avoid all of that stress."
The majority of forums users advised the bride-to-be to go ahead with the wedding celebrations without her sister's involvement, and ignore the family's wishes, however one user urged the poster to think of the potential consequences down the line.
"These decisions have consequences," suggested a woman going by the name Sansa85, "and I encourage the OP to think long and hard about what the consequences might be before making any decisions based on what was a pretty petty list of grievances.
This isn’t some random friend who is a little b****y; this is her only sister.
There could be real fallout from keeping her out, especially if the reason is stupid sibling rivalry things dating back years."