I'm not sure if the NT IP stack was ever BSD, but many of the windows 3.11 and early 95 (before Microsoft natively added support) were from the BSD stack, or at the very least re-implemented the BSD socket API (Most famously Trumpet Winsock). This probably fed the rumours. IIRC winsock was also bundled as an "extras" in some pre-native IP supported versions of NT.
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I'm not sure if the NT IP stack was ever BSD, but many of the windows 3.11 and early 95 (before Microsoft natively added support) were from the BSD stack, or at the very least re-implemented the BSD socket API (Most famously Trumpet Winsock). This probably fed the rumours. IIRC winsock was also bundled as an "extras" in some pre-native IP supported versions of NT.