Instead, they grow against each other creating a weak joint. The effect is similar to hammering in a wedge between them. To prevent this, remove one of the two branches when the tree is young. Branches at those angles should be encouraged by removing competing but less desirable neighbors. Branches larger than that are often heavier than the trunkcan support, and are candidates to break when wind, ice, or snow come along.
Trees grow by adding new layers of wood on the trunk and branches each year.
As the trunk grows, it will strengthen the joints with branches by adding wood around it, like a dowel in a chair leg. Maintain a stable center of gravity. Wind, winter snow loads, or previous loss of a major limb can create situations where the tree's center of gravity is not positioned over the trunk. Then when a severe storm hits, a slight bit of extra weight or wind pressure can break limbs, snap the trunk off, or even topple the tree, roots and all. You can help reposition a tree's center of gravity by selectively removing branches on the leaning side and encouraging branches on the opposite side.