ZWJ
Zero Width Joiner. An invisible Unicode character that joins two or more other characters together in sequence to create a new emoji.
These emojis have ZWJ in them: 💏 👩 ❤️ 💋 👨 👨 ❤️ 💋 👨 👩 ❤️ 💋 👩 💑 👩 ❤️ 👨 👨 ❤️ 👨 👩 ❤️ 👩 👪️ 👨 👩 👦 👨 👩 👧 👨 👩 👧 👦 👨 👩 👦 👦 👨 👩 👧 👧 👨 👨 👦 👨 👨 👧 👨 👨 👧 👦 👨 👨 👦 👦 👨 👨 👧 👧 👩 👩 👦 👩 👩 👧 👩 👩 👧 👦 👩 👩 👦 👦 👩 👩 👧 👧 👨 👦 👨 👦 👦 👨 👧 👨 👧 👦 👨 👧 👧 👩 👦 👩 👦 👦 👩 👧 👩 👧 👦 👩 👧 👧