The advice to adopt two kittens together rather than one is common enough to feel like an automatic best practice, but the actual right choice depends on genuine trade-offs worth weighing honestly rather than assuming one approach is universally superior.
The case for two kittens together
Littermates or similarly-aged kittens raised together typically provide each other with play companionship and continued bite-inhibition practice beyond what a single kitten gets from human interaction alone, and many owners report two kittens settling in with less separation-anxiety-related difficulty than a single kitten facing extended solo hours.
The case for a single kitten
A single kitten typically bonds more intensely and directly with human family members, since there's no feline playmate absorbing some of that attention and social energy — for owners specifically prioritizing a close, primary human-cat bond, a single kitten sometimes develops this more readily than one of a bonded pair.
The genuine cost consideration
Two kittens mean double the veterinary costs, food, and general expenses — this is obvious but worth stating plainly, since the "get two, they'll keep each other company" framing sometimes undersells the real, doubled financial commitment involved.
Compatibility isn't automatic even between littermates
While littermates often bond well, this isn't universal — some sibling pairs show ongoing tension or an uneven dynamic (one dominant, one perpetually avoidant) that doesn't resolve with time the way owners might hope, making even a littermate pairing worth watching rather than assuming guaranteed compatibility.
A reasonable middle path: getting a second cat later
Rather than viewing this as an immediate either-or decision, adding a second cat some months or years after the first, once you understand your first cat's temperament and your own household capacity, is a genuinely reasonable alternative to the immediate two-kitten approach, though it does involve its own separate introduction process rather than kittens who've simply always known each other.
What actually matters most in this decision
Your specific household's realistic capacity — time, space, and financial resources — matters more than a general rule about kittens needing companionship; a single kitten with adequate human attention and appropriate enrichment does perfectly well, making this genuinely a household-fit decision rather than one with a single correct answer.