Even though there is theoretically a 50/50 chance of conceiving either sex, in some families this ratio may be skewed in reality due to for example, an inherited tendency or other factors to have more boys than girls or vice versa.
Did you know that today sperm count is lower in men than say for their forbears due to many reasons eg. higher level of chemical and other pollution, use of laptops, mobile devices, etc.?
Tip: Do NOT place your laptop directly on your lap as there is evidence that 1) electromagnetic radiation as well as the 2) HEAT from your laptop - decreases sperm count!!**
Tip: Similarly with cell-phone storage - avoid storing them in your pocket close to your 'crown-jewels' as that will also reduce sperm count.**
(There are many more tips on the 'do's' and 'don'ts' on how to determine baby gender).
Note: also that pollutants like plastics in the environment eg. food stored or sold in plastic containers, disposable plastic-foam cups, etc., increase oestrogen in the surroundings amongst other things. Higher levels of oestrogen depress sperm count, as well as cause children to mature faster (cf. children are developing breasts at an earlier age.) High stress levels, eg. from work or business, personal financials and / or relationship issues also depress sperm count.
Tip: Don't move around immediately after sex but lie quietly for a while (for the woman) in order to increase the chances of getting pregnant especially if you are using the shallow sex technique (the position often advocated for determining girl gender where you are trying to stack the odds in favour of X-sperm success).
Deep penetration techniques that are recommended for determining boy gender stack the odds in favour of the Y-sperms, which swim faster and so reach the egg faster. Deep methods place the sperm closer to the cervix so the sprinters have a shorter distance to travel to reach their destination before they perish. This is more advantangeous for predicting boy gender especially if you have truly missed your ovulation date because the X-sperms, which are hardier 'long-distance runners' will outlive and beat the Y-sperms to the 'finishing line' - the ovum (egg)! Good, if you are determining girl gender for baby.
Go here to ARM yourself with the correct information on how to predict Baby gender.
**Further reading