To comfort you, I would say that the French never know when to say big or large or wide. Tall is somewhat easier: it is always grand to refer to people.
A few hints about the difference between grand (big, tall, great) and gros (big, fat, wide) in French: • human beings: il est gros (fat), il est grand (tall), c'est un grand homme (great). Intentionally, "grand" is more appreciative than "gros": c'est un gros commerçant (making money); c'est un grand industriel (respectable). • animals: un gros chien (contrary of "petit chien", so rather big); un grand chien (tall and slim) • real things: gros manteau (thick/heavy), grosses chaussures (big/heavy), grande robe (long), grande avenue(wide), grand vin (great wine). • concepts: un grand rire (big), un gros or grand chagrin (deep/great)
When an individual person is qualified as "un homme grand/un enfant grand/une personne grande", it means "tall".
"Un grand homme" is a great man, "un grand enfant" is a big child, and "une grande personne" is a grown-up.
"Une grande famille" should not be "tall" but "large", because it means that it has many members.
If you wanted to say that all members of the family are tall, you would say "tous les membres de la famille sont grands" or "ils sont tous grands dans cette famille".