According to Fabric-node-sdk documentation
For a peer node to become part of a channel, it must be sent the genesis block
According to fabric-documentation
There is one ledger per channel. Each peer maintains a copy of the ledger for each channel of which they are a member.
To join channel peer requires a genesis block, the genesis block is acquired from channel.
So does this mean that channel also holds a copy of ledger?
Edited
For a new network First we create channel and then peers join the channel.
So how the peers will get the genesis block when they yet not part of channel and don't have copy of ledger?
Consider the first peer who is joining channel, no other peers are joined yet.