@sullyfish6,
I think it's all rubbish myself, but if you are born on a cusp day, then your sign depends on the time of day/location where you were born. The sign is on the cusp of both Gemini and Cancer.
Here is a table who reports the date and hour of ingress of Cancer from June 1970 to June 2003 - it's valid for Greenwich Meridian (zero degrees west):
1970 June 21 at 19.43
1971 June 22 at 01.19
1972 June 21 at 07.05
1973 June 21 at 13.00
1974 June 21 at 18.37
1975 June 22 at 00.26
1976 June 21 at 06.24
1977 June 21 at 12.13
1978 June 21 at 18.10
1979 June 21 at 23.56
1980 June 21 at 05.50
1981 June 21 at 11.44
1982 June 21 at 17.23
1983 June 21 at 23.08
1984 June 21 at 05.02
1985 June 21 at 10.44
1986 June 21 at 16.30
1987 June 21 at 22.08
1988 June 21 at 03.56
1989 June 21 at 09.53
1990 June 21 at 15.32
1991 June 21 at 21.18
1992 June 21 at 03.14
1993 June 21 at 09.00
1994 June 21 at 14.48
1995 June 21 at 20.34
1996 June 21 at 02.23
1997 June 21 at 08.20
1998 June 21 at 14.00
1999 June 21 at 19.49
2000 June 21 at 01.47
2001 June 21 at 07.37
2002 June 21 at 13.24
2003 June 21 at 19.10.
For other places in the world, adjust time zones e.g. if you were born in America, subtract 6 or more hours, if you were born in Australia add 8, 9 or 10 hours.
If you were born in England, don't add or subtract anything.